In digital radiography, the following exposure techniques are applied in fluoroscopy systems:
An iontomat chamber is an exposure measurement device used during the exposure of an X-ray film in a destination device, whilst the exposure of digital X-ray recordings takes place behind an X-ray image amplifier, the output fluorescent screen of which is scanned by a television camera, a CCD camera for instance. To do this, in the optical parallel radiation path between the X-ray image amplifier and the television camera, a part of the light is deflected onto a multiplier or a switchable array of photodiodes as light sensors, as disclosed for example in EP 0 362 427 B1. This system is disadvantageous in that two exposure systems are required and the light extraction in the parallel radiation path requires a costly optical solution.